In other words, if a doctor prescribes me a $1000 medicine instead of a $500 one, and a visit to said doctor costs $500, I might not visit him a second time because I've already paid $1000 for the medicine and I don't have enough money for my health anymore. Not visiting your doctor when you need it (for whatever reasons) is bad for the patient.

But even if doctors who needed more patient bookings could attract those bookings by saving patients money then logic would follow that doctors who have room in their schedule would consistently use the app from the article. Yet most doctors aren’t using it at all.

So even if your premise is correct I think you’re greatly overestimating the surplus supply of doctors appointments and underestimating how steep/inelastic the demand curve is for healthcare.

Mostly unrelated, is saying “surplus supply” redundant? I can’t decide.